The present invention relates to a multi-layer sustained release scent emitting article having a high effective scent emitting exposure surface area comprising two barrier layers covering the planar surfaces of the functional ingredient-containing material. The present invention also relates to methods for using such an article for effecting the controlled release of insect repellents, air fresheners, odorants and deodorants over a relatively long period of time and, optionally, in the same time frame effecting an initial "Burst" of the same or different functional materials over a relatively short period of time.
Various articles intended to release a fragrance over a long period of time are well known. The fragrances employed include both aromatic and perfumed compositions. An early form of such device, and one still in use, was a pomander made by studding an apple or orange with cloves and useful as a garment sachet. Another approach still in use is to enclose dried leaves or flower petals in a perforated bag, box or other container. More recently, various solid substrates such as waxes or polymeric materials have been impregnated with fragrances for use, for example, as room fresheners. In such applications, a steady and controlled rate of release of the fragrance from the substrate is a desirable attribute. The uses of waxes or polymeric materials as substrates or carriers has the further advantage that the fragrance-containing materials can readily be formed or cut into virtually any desired shape or size.
As specific examples of the known materials described above, U.S. Pat. No. 3,567,119 to Wilburt discloses a method for incorporating fragrance compounds, oil bouquets or other agents into polymeric or natural materials so that the fabricated product possesses the properties imparted by the agent or agents for a long period of time; this method requires the use of surfactants for incorporating the agents and the duration of the agent in the fabricated product is enhanced by employing antioxidants and/or ultraviolet radiation absorbers. U.S. Pat. No. 3,303,046 to Chebiniak, et al describes a composition containing pores which express liquid upon the application of pressure, formed from mixing an aqueous latex of a polymer with a plasticizer and heating to produce an aqueous composition containing dispersed droplets or plasticizer in which a coloring material may be dispersed. U.S. Pat. No. 4,493,869 to Sweeney, et al describes fragrance-releasing appliques that provide a transparent or translucent substrate bearing microcapsules containing the fragrance in a binder on one surface. U.S. Pat. No. 4,254,179 to Carson, et al describes a method and apparatus for impregnating a porous foam product with a fragrance that can be released over an extended period of time. U.S. Pat. No. 4,257,176 to Hartung, et al describes an insole for footwear that has an odor masking or malodor counteractant material dissolved, trapped or encapsulated in a somewhat resilient resin coating through which it will progressively migrate or bleed under application of foot loads, foot perspiration and elevated foot temperatures to the surface of the coating to be released into the footwear to mask or counteract foot odors. U.S. Pat. No. 4,226,944 to Stone, et al discloses fragrance-emitting articles comprising a polyurethane foam containing a particulate filler and a fragrance material and a method of making such an article.
PCT Application 89/07429 published on Aug. 24, 1989 and assigned to Cygnus Research Corporation claims, inter alia,
"Discloses a method for making a fragrance-releasing device, comprising:
(a) laminating an adsorbent source layer, adapted to initially retain a fragrance in liquid form, to a pressure-sensitive, pharmaceutically acceptable adhesive carrier which defines a basal surface; PA1 (b) depositing a fragrance in liquid form on one face of the adsorbent source layer, whereby the fragrance is incorporated and initially retained therein; PA1 (c) laminating an anchor adhesive layer to the opposing face of the source layer, the anchor adhesive layer comprised of a material that is substantially permeable to the fragrance; and PA1 (d) applying a backing layer to the anchor adhesive layer which defines the upper surface of the device and is substantially permeable to the fragrance." PA1 "(a) a backing layer that is substantially permeable to the fragrance and which defines the upper surface of the device; PA1 (b) an anchor adhesive layer adjacent the backing layer and laminated thereto, wherein the anchor adhesive layer is comprised of a material that is substantially permeable to the fragrance; PA1 (c) a layer of a pressure-sensitive, pharmaceutically acceptable contact adhesive layer which defines the basal surface of the device; and PA1 (d) an adsorbent fibrous source layer in contact with and contained between layers (b) and (c) and into whose void volume at least a portion of layers (a) and (b) has flowed; and PA1 (e) a fragrance dissolved in layer (b), said portion of layer (b) and optionally layer (c) and said portion of layer (c)."
PCT Application 89/07429 further describes a device for the controlled release of fragrance into the atmosphere comprising:
Published United Kingdom Patent Application 2,209,532A published on May 17, 1989 (Applicant: Thermedics Inc.) having a priority in the United States of Sep. 9, 1987, U.S. application Ser. No. 095,055, discloses a fragrance-emitting article or perfume patch which comprises a polyurethane having a perfume dispersed therein wherein in one embodiment of the article there is included a fragrance-emitting member having a fragrance dispersed within the polyurethane layer. A layer of pressure-sensitive adhesive is applied to the article so that it may be adhered to a surface. The polyurethane is formed from a diisocyanate, a macroglycol, and an acrylyl chain terminator to which a photoinitiator and a fragrance oil are added prior to photo-curing. A barrier or support layer is applied by an adhesive or other suitable means to prevent migration of the fragrance oil to the adhesive layer so that no residue of adhesive remains on the surface.
None of the articles of the prior art concern the type of article of the instant invention wherein two barrier layers surround the two exposed surface of a functional ingredient, emitting laminar where the functional ingredient is emitted in a controlled release manner through a "gate" from the edges of the article and/or from defined discreet relatively small surface area sections of the article.